Autophagy and vacuolar biogenesis during the nectary development.

MAIN CONCLUSION: Different autophagy pathways are a driver of vacuolar biogenesis and are development stage specific during the extrafloral nectary development in Citharexylum myrianthum. Plant autophagy plays an important role in various developmental processes such as seed germination, pollen maturation and leaf senescence. However, studies that address the evidence of autophagy and its role in the development of plant glands are scarce and largely restricted to laticifers. Regarding nectary, studies have repeatedly pointed to signs of degradation associated with the end of the secretory cycle, without exploring autophagy. Likewise, the relationship between autophagy and biogenesis of vacuoles remains an unexplored issue. In this study, using conventional and microwave fixation in association with ultracytochemical methods for transmission electron microscopy, we investigated the occurrence of autophagy and its implication in the differentiation of extrafloral nectary in Citharexylum myrianthum (Verbenaceae) under natural conditions, focusing on the vacuole biogenesis. We described a variety of vacuole types associated with the stage of nectary epidermis development, which differs with respect to origin, function and nature of the products to be stored. Three distinct autophagy pathways were detected: macroautophagy, microautophagy (both restricted to the undifferentiated epidermal cells, at the presecretory stage) and megaautophagy (circumscribed to the differentiated epidermal cells, at the postsecretory stage). Our study clearly demonstrated that the vacuole variety and autophagy processes in the nectary epidermal cells are development specific. This study highlights the role of autophagy in vacuole biogenesis and its implications for the development of nectary and opens new venues for future studies on regulation mechanisms for autophagy in plant secretory structures under normal conditions.

Origins of North American arid-land Verbenaceae: More than one way to skin a cat.

PREMISE OF THE STUDY: Verbenaceae originated and initially diversified in South America in wet forest habitats. They have diversified extensively in arid habitats in both South and North America. This study aims to understand the origin of the North American arid-land members of Verbenaceae. METHODS: A phylogenetic approach is used to examine four genera (Aloysia, Citharexylum, Glandularia, Verbena) in three distinct clades with representatives in North American deserts and disjunct South and North American distributions. Phylogenetic analyses were conducted using maximum likelihood and Bayesian approaches. Analyses included both plastid and nuclear DNA regions and include the first study of Citharexylum and an expanded sampling of tribe Verbeneae (Glandularia and Verbena). Ancestral areas were reconstructed for each group. KEY RESULTS: North American desert species of Aloysia and Glandularia were likely derived from ancestors in arid temperate South America, perhaps by long-distance dispersal. The pattern for Verbena was less clear, with evidence from plastid DNA implicating an Andean dispersal route to the North American clade, whereas nuclear data suggest that the Andean and North American species resulted from independent dispersals from southern South America. A previously unrecognized clade of Andean Verbeneae was discovered, raising the possibility of an Andean origin of Verbena or Verbena and Glandularia. North American desert species of Citharexylum represent multiple, independent origins from mesic habitat ancestors in Mesoamerica. CONCLUSIONS: North American arid-zone Verbenaceae are derived from South and Central American ancestors via multiple avenues, including long-distance, amphitropical dispersal, Andean migration corridors, and in situ evolution of desert-adapted species.

Alternating temperature combined with darkness resets base temperature for germination (Tb ) in photoblastic seeds of Lippia and Aloysia (Verbenaceae).

Thermal time models for seed germination assume a continuum of rate responses in the sub-optimal temperature range. Generally, the models describe germination performance in non-dormant seeds at constant temperatures, yet alternating temperature (AT) is a feature of many natural environments. We studied the possible interacting effects of AT on germination progress in photoblastic seeds of three aromatic-medicinal Verbenaceae species in the genera Lippia and Aloysia. For Lippia turbinata f. turbinata and L. turbinata f. magnifolia seed, germination only occurred in light conditions, while for L. integrifolia and Aloysia citriodora it was significantly higher in the light than in darkness. Although relative light germination (RLG) was not different between constant and AT in the sub-optimal range, AT raised the base temperature for germination progress (Tb ) from ca. 3-6 °C in constant temperature to 7-12 °C in AT. Among the species, thermal time for 50% seed germination [θT(50) ] was 55-100 °Cd at constant temperature. Although AT resulted in slight modifications to θT(50) , the germination rate at comparable average temperatures in the sub-optimal range was slower than under constant temperatures. For all species, the proportion of germinated seeds was similar for constant and AT. Our results suggest that an interaction between cool temperature and darkness during AT treatment limits the temperature range permissive for germination in these positively photoblastic seed, reflecting both close adaptation to the natural ecology and niche requirements of the species.

Negative effects of heterospecific pollen receipt vary with abiotic conditions: ecological and evolutionary implications.

BACKGROUND AND AIMS: Studies that have evaluated the effects of heterospecific pollen (HP) receipt on plant reproductive success have generally overlooked the variability of the natural abiotic environment in which plants grow. Variability in abiotic conditions, such as light and water availability, has the potential to affect pollen-stigma interactions (i.e. conspecific pollen germination and performance), which will probably influence the effects of HP receipt. Thus, a more complete understanding of the extent, strength and consequences of plant-plant interactions via HP transfer requires better consideration of the range of abiotic conditions in which these interactions occur. This study addresses this issue by evaluating the effects of two HP donors (Tamonea curassavica and Angelonia angustifolia) on the reproductive success of Cuphea gaumeri, an endemic species of the Yucatan Peninsula. METHODS: Mixed (conspecific pollen and HP) and pure (conspecific pollen only) hand-pollinations were conducted under varying conditions of water and light availability in a full factorial design. Reproductive success was measured as the number of pollen tubes that reached the bottom of the style. KEY RESULTS: Only one of the two HP donors had a significant effect on C. gaumeri reproductive success, but this effect was dependent on water and light availability. Specifically, HP receipt caused a decrease in pollen tube growth, but only when the availability of water, light or both was low, and not when the availability of both resources was high. CONCLUSIONS: The results show that the outcome of interspecific post-pollination interactions via HP transfer can be context-dependent and vary with abiotic conditions, thus suggesting that abiotic effects in natural populations may be under-estimated. Such context-dependency could lead to spatial and temporal mosaics in the ecological and evolutionary consequences of post-pollination interactions.

The interaction apparatus of Asteridiella callista (Meliolaceae, Ascomycota).

We document here for the first time ultrastructural details of the cellular interaction of Asteridiella callista and its host Stachytarpheta mutabilis var. violacea from Costa Rica. A. callista attaches to the host with appressoria, invades the epidermal cell wall and forms an apoplastic complex cisternal net, presumably for nutrient uptake from its host. This unique structure, called an interaction apparatus (Ia), consists of cisternae surrounded by a membrane continuous with the fungal cytoplasmic membrane. Subsequently the apoplastic trunk of the Ia extends into the host epidermal cell wall and contacts the host cytoplasmic membrane. Electron-opaque material, probably of fungal origin appears at the host cytoplasmic membrane. Finally these electron-opaque deposits are encased by host material. Functional and systematical aspects of this interaction scenario are discussed.

[Natural regeneration response in mangroves of the gulf of Urabá (Colombia) to the environmental and intra-annual climate variability]. / Respuesta de la regeneración natural en manglares del Golfo de Urabá (Colombia) a la variabilidad ambiental y climática intra-anual.

The natural regeneration process allows the mangrove forests remain over time. Both, biological and physical factors can affect the establishment and early stages along the development of trees. This study examined the response of natural regeneration of mangroves in the Turbo River delta and El Uno bay (Urabá Gulf, Colombia) to intra-annual environmental variability. We quantified mortality, survival and recruitment of seedlings of three mangrove species, seasonally during one year, in 72 semi-permanent sub-plots of 1 m2. In the sub-plots, the total height and the diameter at the base of the stem of all mangrove seedlings with basal diameter less than 2.5cm were measured. Damage by herbivores was also recorded to each seedling. While Laguncularia racemosa recorded the highest rates of mortality, Rhizophora mangle showed the highest survival rate during the study period, although Avicennia germinans dominated the natural regeneration. Through a Redundancy Analysis these processes were associated to environmental variables such as: Direct Site Factor-DSF (sunlight), sediments input rate, herbivory, distances from mangroves to the river, to inner lakes, and to the coastline. These variables explained 43% of the natural regeneration variation; sedimentation rate was the most important variable, while light was very representative for the R. mangle survival. Based on historical records of precipitation, Turbo River flow rate and associated sediment loads, it was established that during the highest precipitation peak, the survival of all species decreases and during the dry season, when the conditions of flooding and sediments input were lower, it was improved. The results indicated that the sediments input rates and sunlight play an important role in the survival of natural regeneration of evaluated mangrove species.

Respuesta de la regeneración natural en manglares del Golfo de Urabá (Colombia) a la variabilidad ambiental y climática intra-anual / Natural regeneration response in mangroves of the Gulf of Urabá (Colombia) to the environmental and intra-annual climate variability

The natural regeneration process allows the mangrove forests remain over time. Both, biological and physical factors can affect the establishment and early stages along the development of trees. This study examined the response of natural regeneration of mangroves in the Turbo River delta and El Uno bay (Urabá Gulf, Colombia) to intra-annual environmental variability. We quantified mortality, survival and recruitment of seedlings of three mangrove species, seasonally during one year, in 72 semi-perma-nent sub-plots of 1m². In the sub-plots, the total height and the diameter at the base of the stem of all mangrove seedlings with basal diameter less than 2.5cm were measured. Damage by herbivores was also recorded to each seedling. While Laguncularia racemosa recorded the highest rates of mortality, Rhizophora mangle showed the highest survival rate during the study period, although Avicennia germinans dominated the natural regeneration. Through a Redundancy Analysis these processes were associated to environmental variables such as: Direct Site Factor-DSF (sunlight), sediments input rate, herbivory, distances from mangroves to the river, to inner lakes, and to the coastline. These variables explained 43% of the natural regeneration variation; sedimentation rate was the most important variable, while light was very representative for the R. mangle survival. Based on historical records of precipitation, Turbo River flow rate and associated sediment loads, it was established that during the highest precipitation peak, the survival of all species decreases and during the dry season, when the conditions of flooding and sediments input were lower, it was improved. The results indicated that the sediments input rates and sunlight play an important role in the survival of natural regeneration of evaluated mangrove species.

En los bosques de mangle, tanto factores biológicos como físicos, afectan el establecimiento y los estados tempranos de desarrollo de los árboles y determinan la distribución espacial de las especies. Se evaluó la respuesta de la regeneración natural de los manglares del delta del río Turbo y la bahía El Uno a la variabilidad ambiental y climática intra-anual. Se cuantificaron la mortalidad, la sobrevivencia y el reclutamiento de las plántulas de tres especies, estacionalmente durante un año. Avicennia germinans dominó la regeneración natural, Rhizophora mangle presentó la mayor la supervivencia y Laguncularia racemosa la mayor mortalidad. Estos procesos se asociaron principalmente con el aporte de sedimentos aluviales, la disponibilidad de luz, la herbivoría, la distancia al río, a las lagunas internas y a la línea de costa, las cuales explicaron el 43% de la variación en la regeneración. La sedimentación fue la variable más importante para el reclutamiento de A. germinans, mientras la luz fue muy representativa para la supervivencia de R. mangle. Con base en registros históricos de precipitación, caudales y carga de sedimentos, se estableció que en la época con mayor precipitación se presenta un descenso en la supervivencia, y en la época seca se favorece el balance entre el reclutamiento y la mortalidad. Los resultados indicaron que la precipitación, el aporte de sedimentos y la luz desempeñan un papel importante en el proceso de la regeneración de las especies evaluadas.

[Identification characters of leaf morphological and venation pattern of Baphicacanthus cusia with its confused herb Clerodendrum cyrtophyllum].

OBJECTIVE: To study the identification characters of Baphicacanthus cusia and its confused herb Clerodendrum cyrtophyllum and establish an identification method. METHODS: LMVP (leaf morphological-venation pattern for identification Chinese herbs) and QAERM (quantitatively analyze and evaluate reliability for the method of identification Chinese herbs) were applied for the study. RESULTS: The main differences of the leaf were as follows: Baphicacanthus cusia: leaf base attenuate, dry leaves deep dull blue green, spindle spots, no or small glandular scales somewhere, the limit between midrib and petiole was not clear, below undermost secondary vein some tertiary veins issue from midrib; Clerodendrum cyrtophyllum: leaf base not attenuate; dry leaves yellow green, green, green yellow, yellow brown, no spindle spots, densely covered by glandular scales,the limit between midrib and petiole was clear, below undermost secondary vein none tertiary veins issue from midrib. With the mentioned six groups of key differences, the both plants could be successfully identified from each other. The accuracy of identification results (AC) was from 98.5% to 99.2%, the repeatability of identification results: agreement rate for observation (ARO) was 97.7% and Kappa value was 0.95. CONCLUSION: The established method is simple, rapid, economic and reliable.

Disturbance governs dominance of an invasive forb in a temporary wetland.

Dominance of invasive species is often assumed to be due to a superior ability to acquire resources. However, dominance in plant communities can arise through multiple interacting mechanisms, including disturbance. Inter-specific competition can be strongly affected by abiotic conditions, which can determine the outcome of competitive interactions. We evaluated competition and disturbance as mechanisms governing dominance of Phyla canescens (hereafter lippia), an invasive perennial forb from South America, in Paspalum distichum (perennial grass, hereafter water couch) meadows in floodplain wetlands of eastern Australia. Water couch meadows (in the study area) are listed under the Ramsar Convention due to their significance as habitat for migratory waterbirds. In the field, we monitored patterns of vegetation boundaries between the two species in response to flooding. Under controlled glasshouse conditions, we explored competitive interactions between the native water couch and lippia subject to different soil moisture/inundation regimes. We did this using a pairwise factorial glasshouse experiment that manipulated neighbor density (9 treatments) and soil moisture/inundation (4 treatments). In the field trial, inundation increased the cover of water couch. Under more controlled conditions, the invader had a competitive effect on the native species only under dry soil conditions, and was strongly inhibited by inundation. This suggests that dry conditions favor the growth of the invader and wetter (more historical) conditions favor the native grass. In this system, invader dominance is governed by altered disturbance regimes which give the invader a competitive advantage over the native species.

Effect of lemon verbena supplementation on muscular damage markers, proinflammatory cytokines release and neutrophils' oxidative stress in chronic exercise.

Intense exercise is directly related to muscular damage and oxidative stress due to excessive reactive oxygen species (ROS) in both, plasma and white blood cells. Nevertheless, exercise-derived ROS are essential to regulate cellular adaptation to exercise. Studies on antioxidant supplements have provided controversial results. The purpose of this study was to determine the effect of moderate antioxidant supplementation (lemon verbena extract) in healthy male volunteers that followed a 90-min running eccentric exercise protocol for 21 days. Antioxidant enzymes activities and oxidative stress markers were measured in neutrophils. Besides, inflammatory cytokines and muscular damage were determined in whole blood and serum samples, respectively. Intense running exercise for 21 days induced antioxidant response in neutrophils of trained male through the increase of the antioxidant enzymes catalase, glutathione peroxidase and glutathione reductase. Supplementation with moderate levels of an antioxidant lemon verbena extract did not block this cellular adaptive response and also reduced exercise-induced oxidative damage of proteins and lipids in neutrophils and decreased myeloperoxidase activity. Moreover, lemon verbena supplementation maintained or decreased the level of serum transaminases activity indicating a protection of muscular tissue. Exercise induced a decrease of interleukin-6 and interleukin-1ß levels after 21 days measured in basal conditions, which was not inhibited by antioxidant supplementation. Therefore, moderate antioxidant supplementation with lemon verbena extract protects neutrophils against oxidative damage, decreases the signs of muscular damage in chronic running exercise without blocking the cellular adaptation to exercise.

Phenotypic divergence during the invasion of Phyla canescens in Australia and France: evidence for selection-driven evolution.

Rapid adaptive evolution has been advocated as a mechanism that promotes invasion. Demonstrating adaptive evolution in invasive species requires rigorous analysis of phenotypic shifts driven by selection. Here, we document selection-driven evolution of Phyla canescens, an Argentine weed, in two invaded regions (Australia and France). Invasive populations possessed similar or higher diversity than native populations, and displayed mixed lineages from different sources, suggesting that genetic bottlenecks in both countries might have been alleviated by multiple introductions. Compared to native populations, Australian populations displayed more investment in sexual reproduction, whereas French populations possessed enhanced vegetative reproduction and growth. We partitioned evolutionary forces (selection vs. stochastic events) using two independent methods. Results of both analyses suggest that the pattern of molecular and phenotypic variability among regions was consistent with selection-driven evolution, rather than stochastic events. Our findings indicate that selection has shaped the evolution of P. canescens in two different invaded regions.

Physiological and isotopic (delta(13)C and delta(18)O) responses of three tropical tree species to water and nutrient availability.

Water-use efficiency and stable isotope composition were studied in three tropical tree species. Seedlings of Tectona grandis, Swietenia macrophylla and Platymiscium pinnatum were grown at either high or low water supply, and with or without added fertilizer. These three species previously exhibited low, intermediate and high whole-plant water-use efficiency (TE) when grown at high water supply in unfertilized soil. Responses of TE to water and nutrient availability varied among species. The TE was calculated as experiment-long dry matter production divided by cumulative water use. Species-specific offsets were observed in relationships between TE and whole-plant (13)C discrimination (Delta(13)C(p)). These offsets could be attributed to a breakdown in the relationship between Delta(13)C(p) and the ratio of intercellular to ambient CO(2) partial pressures (c(i)/c(a)) in P. pinnatum, and to variation among species in the leaf-to-air vapour pressure difference (v). Thus, a plot of v.TE against c(i)/c(a) showed a general relationship among species. Relationships between delta(18)O of stem dry matter and stomatal conductance ranged from strongly negative for S. macrophylla to no relationship for T. grandis. Results suggest inter-specific variation among tropical tree species in relationships between stable isotope ratios (delta(13)C and delta(18)O) and the gas exchange processes thought to affect them.

Micropropagation of Glandularia perakii Cov. et Schn. (Verbenaceae), a native species with ornamental potential.

Glandularia perakii is a perennial species with beautiful violet flowers that grows in the stony soil of Mendocine pedemont. A plentiful and prolonged flowering confers it an important ornamental potential. In this paper, a method of propagation of G. perakii from nodal segments is reported. Proliferating microshoot cultures were obtained by placing nodal segment on Murashige and Skoog medium (MS) supplemented with 20 g.L-1 of sucrose without growth regulators. In this medium multiplication rate after 20 days was 7.9. Rooted plants were acclimatized successfully.

Micropropagation of Glandularia perakii Cov. et Schn. (Verbenaceae), a native species with ornamental potential

Glandularia perakii is a perennial species with beautiful violet flowers that grows in the stony soil of Mendocine pedemont. A plentiful and prolonged flowering confers it an important ornamental potential. In this paper, a method of propagation of G. perakii from nodal segments is reported. Proliferating microshoot cultures were obtained by placing nodal segment on Murashige and Skoog medium (MS) supplemented with 20 g.L-1 of sucrose without growth regulators. In this medium multiplication rate after 20 days was 7.9. Rooted plants were acclimatized successfully. (AU)

Micropropagation of Glandularia perakii Cov. et Schn. (Verbenaceae), a native species with ornamental potential

Glandularia perakii is a perennial species with beautiful violet flowers that grows in the stony soil of Mendocine pedemont. A plentiful and prolonged flowering confers it an important ornamental potential. In this paper, a method of propagation of G. perakii from nodal segments is reported. Proliferating microshoot cultures were obtained by placing nodal segment on Murashige and Skoog medium (MS) supplemented with 20 g.L-1 of sucrose without growth regulators. In this medium multiplication rate after 20 days was 7.9. Rooted plants were acclimatized successfully.

Factors limiting the intertidal distribution of the mangrove species Xylocarpus granatum.

The tree species Xylocarpus granatum is commonly described as occurring in the upper intertidal zone of mangrove forests, but mature trees are occasionally found at lower elevations. In the Utwe River basin, on the Pacific island of Kosrae, we investigated the relative importance of several biotic and abiotic factors that may control the intertidal distribution of X. granatum. Factors we evaluated included differential seed predation across the lower, mid, and upper intertidal zones and seedling responses to salinity, tidal flooding, and shade. Seed predation was 22.4% over the first 34 days and varied little among zones or in gaps versus under the forest canopy. By day 161, there were still no differences in seed mortality, but a significant difference was found in seedling establishment, with much greater establishment in the upper intertidal plots. X. granatum seedlings in a greenhouse experiment exhibited greater growth in freshwater than seedlings in 23 ppt salinity, which is typical of salinity levels found in the mid intertidal zone in our field study sites in Micronesia, where mature X. granatum trees are generally absent. Seedlings grown in 23 ppt salinity, however, exhibited few visible signs of stress associated with patterns in growth. Seedlings grown in a simulated tidal flooding treatment (with 23 ppt salinity) also showed few signs of stress. Growth declined dramatically under 80% shade cloths, but there were few interactions of shading with either 23 ppt salinity or simulated tidal flooding. Differential seed predation is not likely to be the primary factor responsible for the intertidal distribution of X. granatum on Kosrae. However, seedling tolerance of flooding or salinity may be more important, especially relative to a potential contribution to secondary stress mortality. Other factors may ultimately prove to be more critical, such as physiological effects of salinity on seed germination, effects of tides on seed dispersal and rooting, or differential herbivory on seedlings.

In vitro regeneration of roots of Phyla nodiflora and Leptadenia reticulata, and comparison of roots from cultured and natural plants for secondary metabolites.

Adventitious roots, generated using leaf explants of P. nodiflora, and meristem explants of L. reticulata, were cultured on Murashige and Skoog (MS) medium supplemented with napthylacetic acid (2 microM) and indole butyric acid (3 microM) respectively. After 30 days, subculturing of roots in liquid MS medium with napthylacetic acid (1.5 microM) for P. nodiflora and indole butyric acid (3 microM) for L. reticulata afforded considerable increase in root mass. HPTLC profiles and microscopic examination of transverse sections of in vitro and naturally grown roots provided information on secondary metabolite accumulation vis-à-vis developmental stages of the root.

[Insect community and its diversity in Mangrove forest at Yingluo Bay of Guangxi].

The insect community and its diversity in mangrove forest at Yingluo Bay of Guangxi were studied in 1995-1996. The results show that there were 195 insect species in the mangrove area, dominated by Crematogaster rogenhoferi, Camponotus tokioensis and Dichocrocris chorophanta. The diversity of insect community was higher in the inside beach than in the middle and outside beaches. Tides and windstorms were the important factors that decided the community composition levels. The principal component affecting the diversity was the species evenness in the inside, middle and outside beaches.